Study On Loading Characteristics Of Orifice Compensated Aerostatic Thrust Bearing

Development of space technology, microelectronic technology and precision machining technology demand high accuracy. Attribute to its advantages of high accuracy, anti-friction, clean and health, aerostatic bearing is widely used in spaceflight, pharmaceuticals industry, food service industry, high precision machine tool and measuring instrument areas. In ground-based spaceflight and docking simulation system, it is necessary to simulate a zero-genvironment officeenvironment completely. As an important support unit, aerostatic thrust bearing plays a significant part in air bearing testbed,which is designed for spaceflight and docking simulation system. And the demand for improvement of load-carrying capacity and optimization of throttlling effect of restrictor become one of the most important contents in theoretical research of aerostatic lubrication and design of air bearing.Traditional aerostatic thrust bearing mostly use orifice inlet method which is the earilest and the most pervasive throttle in theoretical and experimental study. In past researches, domestic and foreign scholars always use experimental formula and engineering calculating method in design and election. And they devide orifice inlet into orifice compensation and inherent compensation according to its throttling effect. Putting forward along with entrance effect and shock wave assumption, simplified model composed by isentropic flow in orifice and isothermal flow in gas film is too rough to meet the need for precise answers to performance characteristics of aerostatic thrust bearings in the serious reaches of contemporary science. At present, making an accurate description of orifice restrictor and improving throttle operating principle instead of requirements of high supply gas pressure and thinner gas film under current conditions is of far reaching importance for further enriching and improving design theories for aerostatic thrust bearing, develop fully orifice compensation's potential and capability, use less energy, and have lower costs on high-precision processing technology.Given above consideration and current research situation analysis of orifice compensated aerostatic thrust bearing of domestic and foreign scholars, fulfilled mathematical model of the whole flow process from inlet to outlet is established according to gas lubrication theory, relations and limitaion among all structural paprameters around the orifice inlet. For all possibilities of flow condition and throttling tpyes in the whole region, coupling compressible nonsteady Reynolds equation with boundary conditions, pressure distribution of the air film can be obtained. Therefore the load-carrying properties of air bearing can be obtained, as well as the corresponding conclusions. On base of theoretical analysis, we take multi-inlet orifice compensated aerostatic thrust bearing as an example to disclose influence of detailed parameters on load-carrying capacity of air bearing with different throttling modes in possible working conditions. characteristics and differences of air bearings with different throttling modes are Summarized when they are in normal condition, tilt condition and even interfered environment. In this way, you can choose air bearing with proper throttling mode and optimized parameters of as needed. the test investigation on the static characteristics, anti-tilt characteristics and dynamic characteristics is performed.The results show that the models and research results in this dissertation are available and reliable. The results of this paper further enrich the applications of air lubrication theory to aerostatic bearing design. And it also provides a series of comprehensive methods for selection and use of aerostatic thrust bearing in practical production.